Genome-wide characterization of cucumber methylesterase genes and the phytohormone-mediated response to salt stress

• Identification of the genome-wide characteristics of the thirteen MES genes from cucumber. • Based on phylogenetic analysis, motif distributions, and gene structures, the CsMES gene family was classified into three distinct groups. • CsMESs play an essential role in regulating plant responses to SA and JA. • CsMES6, CsMES9 and CsMES13 can be further focused on the localization and function roles. Cucumber ( Cucumis sativus L.) is an economically important vegetable crop but is susceptible to salinity stress. Methylesterases (MES) hydrolyze the methyl esters of salicylic acid (SA) and jasmonic acid (JA), which play important roles in plant stress response. Currently, the role of MES in salt-stress response has not been systematically studied in cucumber. In this study, we conducted a comprehensive analysis of the MES gene family leveraging the near-complete cucumber reference genome. We identified thirteen CsMES genes which grouped into three clades based on phylogenetic analyses, and examined their gene structure, domains and conserved motifs. We further categorized the cis-acting elements within the promoter regions of the CsMES genes into four functional types: light, environmental stress and hormone response, and plant growth and development. The expression patterns of CsMES genes exhibited notable diversity across various tissues. SA and JA treatments effectively alleviate salt-induced damage in cucumber seedlings. RT-qPCR analysis of CsMES genes expression under salt stress with SA or JA application suggests that these hormones mitigate salinity stress by modulating CsMESs expression. Collectively, these findings enhance our understanding of the structural and functional roles of MES genes in cucumber.